U.S. Pat. No. 3,952,320 to Richard Blount discloses an electric multiple flash lamp arrangement having the lamps connected to a circuit board which carries the sequential firing circuitry and is provided with a pair of connectors for attachment of the flash lamp array to a camera. In a known multiple flash arrangement of this kind, eight flash lamps are provided on the circuit board. These flash lamps are arranged in two rows of four lamps, one above the other. The flash lamps are electrically connected in such a way that fires the upper group of four lamps. By turning said arrangement 180.degree. and reinserting the remaining connector into the flash lamp socket, the remaining group of four flash lamps can be ignited and such an arrangement eliminates or reduces the undesirable "red eye" effect. In related U.S. Pat. No. 3,894,226 to James M. Hanson, there is disclosed such a photoflash lamp array having means for preventing electrical shorting of the circuitry on the circuit board with an insulating sheet member which may be made of plastic and is interposed between the reflector unit of the arrangement and the circuit board. The insulating sheet may also be provided with openings over underlying radiation-sensitive switches in the lamp firing circuitry to permit radiation transfer from the flashing lamps to said radiation-sensitive switches.
While the above summarized electrical insulation achieves the desired purpose, it is an object of the present invention to provide an improved electrical insulation which is integral with the circuit board and has other advantages. Particularly, the present insulation provides a hermetic seal for the underlying switching elements from environmental conditions. Said insulation can be used with radiation-responsive switching elements, of the type above referenced, as well as with voltage-responsive switching elements connected to the circuitry which are converted to an electrically conductive state by the lamp firing pulse. Voltage responsive switches operating in this manner are disclosed in U.S. Pat. No. 3,532,931, Cote et al., which is also assigned to the assignee of the present invention. The present insulation coating further provides better containment of the switch material when being converted during circuit operation. The present insulation still further reduces switch abrasion during manufacture of the flash lamp array.